Elevated levels of PCBs in loon eggs

MOULTONBOROUGH — The Loon Preservation Committee has discovered elevated levels of chemical contaminants in two inviable Common Loon eggs collected from failed nests on Province Lake in Effingham/Wakefield, including polychlorinated biphenyl ethers (PCBs, industrial insulating agents), dioxin-like compounds (byproducts of industrial processes), and chlordane (a pesticide).

The effects of these contaminants on loons are unknown. However, both eggs, collected in 2016 and 2023 but only recently tested by the Loon Preservation Committee, contained levels of contaminants that were 3-9 times higher than those shown to affect the health and/or reproductive success of other bird species. PCB results for the 2016 egg were 21,900 parts per billion and 58,500 parts per billion for the 2023 egg, compared with a statewide average of 1,934 parts per billion. The level of PCBs seen in the 2023 Province Lake egg was last recorded at the height of PCB contamination in the 1970s, and the level of dioxin-like compounds and chlordane in that egg were the highest the committee has ever recorded. The Loon Preservation Committee is authorized by state and federal permits to collect unhatched, inviable eggs for research purposes from failed nests of Common Loons, a threatened species in New Hampshire. To date, they have tested 121 loon eggs collected from 47 lakes throughout the state for these contaminants.